The invention relates to a control arrangement for the supply of lubricant to various bearings of an infinitely variable traction roller transmission or other apparatus having various hydrostatic bearings exposed to different loads under different operating conditions.
In traction roller transmissions, the traction rollers are disposed between, and in engagement with, toric discs and mounted on support trunnions which, when pivoted, cause engagement of the traction rollers with the toric discs in circles of varying diameters depending on the desired transmission ratio. The toric discs are mounted on input and output shafts and held in engagement with the traction rollers by axial thrust bearings which are subjected to varying loads depending on the torque transmitted through the transmission and depending on the pivot position of the traction rollers, that is, on the transmission ratio at which the transmission is operating. For any particular transmission ratio a change of torque results in a corresponding change in the bearing loads; however, any change in the transmission ratio results in different load changes for the bearings even if the power supplied to the transmission remains unchanged.
Generally, the load on the toric output disc bearing decreases as the speed-up ratio and the speed of the output shaft increase whereas the load on the toric input disc bearing increases and vice versa. If the axial thrust bearings of the toric disc are hydrostatic bearings supplied by a common lubricant source, problems in the lubricant distribution may arise: On one hand, it is necessary to insure sufficient lubricant supply to the higher loaded bearing, and on the other hand, it would be advantageous to supply an increased amount of lubricant to the lower loaded, high speed, disc bearing in order to increase the lubricant film thickness in the bearing and thereby substantially decrease shear losses.